"Any land areas once covered by glaciers should be screened for fractures," she said, "particularly if those areas are candidates for a landfill site, livestock waste facility or other use that could potentially endanger the water supply."
One way researchers search for the presence of fractures in an area is to dig test pits, Christy said.
"Some investigators have claimed that they have never seen soil fractures in years of experience with excavating tills," Christy said. "But looking at a freshly bulldozed site can be misleading. Earth moving equipment tends to cover fractures that could be found if you follow careful procedures in excavating a pit."
For example, one study reported in the special issue involved a test pit Christy and several colleagues dug in Madison County to search for evidence of fractures. The pit was 33 feet wide by 82 feet long by 12 feet deep. Their analysis suggested that 7 percent of the ground area uncovered by the pit was affected by fractures.
In addition, Christy and her colleagues conducted tests that estimated a molecule of water could move 155 inches (3.9 meters) through a fracture in this test pit during one year, but only 14 inches (0.4 meters) when moving through unfractured soil.
"Our research suggests that substantial amounts of water and
contaminants can move through fractures in the glacial till,"
Christy said, adding that there is ev
'"/>
Contact: Julie Weatherington-Rice
Weathringtn-Rice.1@osu.edu
614-292-3171
Ohio State University
2-Jan-2001